Floating head for heat exchangers



Feb. 18, 1941. M. SACK FLoA'mx HEAD Fon HEAT XEXCHANQERS Filed. Feb. l1, 1939 2 Sheets-Sheet 1 Feb. 1 8, 1941. M. sAcK FLOAT-ING HEAD FOR HEAT EXCHANGERS Filed Feb. 11|, 1939 2 Sheets-Sheet 2 Patented Feb. 18, 1941 UNITED STATES FLoA'riNG HEAD Vogt Machine poration of Kentucky PATENT OFFICE assignor to Henry Co., Inc., Louisville, Ky., a cor- Application February 11, 1.939, Serial No. 255,990

3 Claims.

This invention relates to heat exchanger of the shell-and-tube type, in which a bundle of tubes having their opposite ends fixed in tube sheets are so placed in the shell that while one tube sheet is anchored with respect to the shell, the opposite tube sheet is freely slidable relative to the shell, to permit unrestrained expansion and contraction of the tubes relative to the shell.

The floating tube sheet in this type of heat exchanger carries a cap which forms with the tube sheet a sealed chamber at the end of the tube bundle for receiving the uid which circulates through the tubes. 'I'his cap moves with the oating tube sheet, and the entire assembly at that end of the tube bundle is known as the floating head. In this type `of heat exchanger, the tube bundle, including the oating tube sheet, after removal of the cap, is of a diameter sufficiently small to permit the ready removal of the unit, including the tubes and both tube sheets, from the shell, for purpose of repair and periodic cleaning, upon detachment of the anchored tube sheet from the shell.

In order to effectively seal the Lconnection between the floating tube sheet and the 'cap of the floating heat, a very tight joint between them must be provided. l In my Patent No. 1,895,735, granted January 31, 1933, of which the present invention is an improvement, I have provided bolts passing through portion of the bolt to bend backwardly, sometimes i resulting in the fracture of the "between the toe and shank. and

ducingthe clamping -v pressure between the bolt and-tubel sheet andcausing the toe of the bolt to bear unevenly against the tube sheet with the greatest pressure at the extreme edge of the tube sheet, sometimes resulting in crushing of the metal of the tubesheet.

One of the objects of the present invention is to provide a construction in which the cap is providd with a downwardly extending. ange, which in the normal tight position of the bolts extends bolt at the angle in any event, re-

normal posidownwardly below the horizontal plane of the angle Ibetween the shank and the toe of the bolt. In other words, said flange backs up the bolts, including the toe portions, so as to resist the backward bending tendency of the boltsl when under 5 clamping pressure.

Another object of the present invention is to provide the cap with individual recesses for the toe portions of the bolts, into which the bolts drop only when the toe portions are in position 10 to engage the lower face of the tube sheet. this giving an indication to the workman who is tightening or loosening the bolts from the outside of the cap, as to whether the bolts are in position to engage the tube sheet, or whether the toe por- 15 tions are not in sidewise position with respect to i the tube sheet, clearing the latter so that the cap can be removed.

Still another object of the invention is to provide a bolt of increased massv and diameter in the 20 lower shank portion and 'in the toe portion, that is, in those portions which surfer the bending stress so that they will not bend outwardly, and

that the flat and extensive area of contact between the toes of the bolts and the tube sheet 25 will be preserved.

Other objects of the invention will appear as the following description of a preferred and practical embodiment thereof proceeds.

In the drawings throughout the several figures of which the same reference characters have been employed -to designate identical parts:

. Figure 1 is a longitudinal section through that portion of a heat exchanger of the type described which embraces the iioating head;

Figure 2 isl a diametrical section taken along the li'ne 2-2 of Figure 1, viewed in the direction of the arrows:

Figure 3 is a perspective view of the cap; and

Figure 4 is a perspective view of the bolt. 40

Referring now in detail to the several gures, the numeral I represents in general the shell, having the end ange 2. Within the shell is the tube bundle 3, composed of a plurality of tubes 4. It will be understood that means are pro- 4, videdin that part of the heat exchanger which is not shown, for causing the fiuid within the tubes to iiow into the floating head from a certain group of the tubes, and then to flow out from the head into another group of the tubes, this system of circulation being conventional in the art. The ends 5 of the tubes 4 are xedin the floating tube sheet 6. Said tube sheet is small enough in diameterto pass through the shell -l as aunit with the tube bundle, ln order to permit removal of the tube bundle by drawing it out through the end of the' heat exchanger which is not shown. The open ends 5 of the tubes communicate with a chamber 1 formed within the cap 8. Said cap has an internal rabbet 9 against which the upper peripheral margin of the tube sheet 6 seats in a fluid tight manner, a gasket I0 intervening. The cap 8 has a rim II which extends beyond the rabbet 9 and is formed with a peripheral series of bolt holes I2 formed outside of the circle which represents the diameter of the tube sheet 6. The rim II is provided with a flange I3, which extends downwardly to a plane below the plane of the lower surface of the tube sheet 6, when said tube sheet is resting against the rabbet 9 Said bolt holes at their inner ends debouch into recesses I4, which open into the inner face of the flange I3, as is best shown in Figures 3 and 4. Said recess-es open through the front face of the ange I3, as is indicated at I5 in Figures 3 and 4, thus having a non-round cross-section in a plane diametrical with respect to the heat exchanger. The recesses I4 are of such depth that their bottom walls, indicated by the dotted line I6 in Figure 1, extend slightly outwardly with respect to the plane of the inner face of the tube sheet 6. The bolt holes I2, as' is shown in Figure l, are preferably of two diameters, corresponding to the shape of the bolts, which latter are best shown in Figures 1 and 4. Said bolt holes have an outer part of relatively small diameter and an inner part, relatively enlarged. The bolts, which in general are designated by the reference character 2|, comprise a threaded shank portion I1 of relatively small diameter, and a lower shank portion I8 of larger diameter, and a toe I9, which is offset at right angles from the shank of the bolt, and being preferably greater in cross-sectional area than the enlarged portion I8 of the shank. The toe I9 is preferably rectangular in cross-section, providing a broad at face 20 for,

direct engagement with the lowery peripheral margin of the tube sheet.

It will be observed from Figure 1 that when the bolts 2I are in clamped relation to the tube sheet, there is necessarily a slight clearance 22 between the back of the bolt and the flange I3. The massive portion of the shank I8 and of the toe I9, prevents any backwardbending of the bolt through any normal sealing pressure between the toe 20 and the tube sheet 6. The large mass of the bolt, particularly back of the angle between the toe and shank portion, prevents'any undue strain or fracture of the bolt at the apex of this angle, due to normal clamping pressure. The broad flat face 20, therefore, rests true against an extensive area of the tube sheet, distributing the clamping pressure and preventing crushing of the tube sheet. Should extraordinary pressure loe-brought upon the bolts through excessive tightening of the nuts 23, so that the bolts do bend back throughout the extent of the small clearance 22, further outward deflection of the bolts is prevented by the :flange I3, which not only backs up the enlarged portion of the shank of the bolt, but also the back of the toe 2U, which in the position illustrated in Figure 1 is seated within the recess I4.

When a wrench is brought to bear upon the nuts 23 in the act of loosening the bolts 2I for 'removing the cap 8, there is no chance of the bolt turning with the nut, for the position of the toe 20 in the correspondingly shaped recess I4 absolutely prevents rotation of the shank of the bolt, so that the nut must loosen. When the nut has been backed off on the shank a suflicient distance to cause the toe to be pushed out of recess I4, the shank of the bolt can then be rotated so as to cause the toe to move out of the way of the tube sheet B. When the bolts are in this position, the cap can be removed endwlse from the tube sheet. In replacing the cap 8, after it has been positioned with the tube sheet resting against the rabbet 9, the Workman can pull outward against the shank of the bolt at the same time rotating the bolt until the toe falls into the recess. He then knows that the toe is projecting beneath the tube sheet, and the bolt is in position to be tightened. The nut may then be drawn up to the desired degree of tightness without any chance that the shank of the bolt will turn and throw the toe of the bolt out of operative position.

A cover 24 bolts upon the flange 2 of the shell, and is removed in order to give access to the cap 8 for removing the latter.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of the invention, it will be understood to those skilled in the art that the specific details of construction as shown and described, are to be regarded as illustrative and not as restricting the scope of the invention 'as defined in the appended claims.

What I claim is:

1. A floating head for shell-and-tube type heat exchangers comprising a tube sheet having a tube bundle fixed thereto, extending from its inner face and opening in its outer face, a cap closed at one end and having an interior annular shoulder in an intermediate depth plane forming a seat engaging the margin of the outer face of said tube sheet, a chamber being thus defined between the closed end portion of said cap and said tube sheet, with which chamber the tubes of said tubebundle communicate, said cap having a peripheral flange closely surrounding the peripheral edge of said tube sheet and of greater depth than the thickness of said edge, an annular series of bolt holes through said flange close to the inner surface thereof and axially perpendicular to the plane of said seat, the ends of said bolt holes which open in the free end of said flange being expanded to form recesses opening in the inner face of said flange, toe bolts having their Shanks in said bolt holes and having angular portions in said recesses adapted to contact the margin of the inner face of said tube sheet, the walls of said bolt holes intersecting the plane in which said angular portions contact `said margin, and seating close against said bolts on that side radially remote from said tube sheet to afford support to said bolts back of the angle between saidshanks and said angular portions, to resist outward bending of said angular portions, relative to said Shanks under the clamping pressure of said bolts against said tube sheets.

2. A floating head for shell-and-tube type heat exchangers comprising a tube sheet having a tube bundle fixed thereto, extending from its inner I face and opening in its outer face, a cap closed at one end and having an interior annular shoulder in an intermediate depth plane forming a seat engaging the margin of the outer face of said tube sheet, a chamber being thus defined between the closed end portion of said cap and said tube sheet, with which chamber the tubes of said tube bundle communicate, said cap having a peripheral flange closely surrounding the 75 portions nonrotatably received ansa-iva depth than the thickness of said edge, an annular series of bolt holes through said ange close to the inner surface thereof and axially perpendicular to the plane of said seat, the ends of said bolt holes which open in the i'ree end of said ange being expanded to form recesses opening in the inner face of said ange, toe bolts having their shanks in said bolt holes and having angular in said recesses adapted to contact the margin of the inner face of said tube sheet, the walls of said bolt holes intersecting the plane in which said angular portions contact said margin, and seating close against said bolts on that side radially remote from said tube sheet, to aiord support to said bolts back of the angle between said shanks and said angular portions, to resist outward bending of said angular portions relative-to said shanks under the clamping pressure of said bolts against said tube sheet.

3. A floating head for shell-and-tube type heat exchangers comprising a tube sheet' having a tube bundle fixed thereto, extending from its inner' face and opening in its outer face, a cap closed at one end and having an interior annular shoulder in an'intermediate depth plane forming a seat engaging the margin of the outer face of said tube sheet,I a chamber being thus defined between the closed end portion of said cap and said tube sheet, with which chamber thetubes of said tube bundle communicate, said cap having a peripheral ilange closely surrounding the peripheral edge of said tube sheet and of greater depth than the thickness of said edge, an annular 'series of bolt holes through said flange close to the inner surface thereof and axially perpendicular to the plane of said seat, the ends of said bolt holes which open in the free end of said ilange being expanded to form recesses opening in the inner face of said iiange, toe bolts having their shanks in said bolt holes with threaded ends extending outwardly from the closed end of said cap, and having angular portions in said recesses adapted to contact the margin ofthe inner face of said tube sheet, the walls of said bolt holes intersecting the plane in which said angular -portions contact said margin, and seating close against said bolts on that side radially remote from said tube sheet to said bolts back of the angle between said Shanks and said angular portions, to resist outward bending of said angular portions, relative to said shanks-under the clamping pressure of said bolts against said tube sheets.

MELVIN SACK.

afford support to i 

